Dental casting apparatus



ATTORNEYJ Feb. 23, 1932. l M. s. sHAPlRo DENTAL CASTING APPARATUS Filed May 6, 1929 @MG/M lll 27T/Wj. MQW

Feb. 23, 1932. M. s. sHAPlRo 1,846,913

DENTAL CASTING APPARATUS Filed May 6, 1929 2 Sheets-Sheet 2 ATTORNEYS Patented Febg23, 1932 -muren strates MAX S. SHAPIR, BROOKLYN, NEW YORK DENTAL onetime. APPARATUS Application filed May 6, 1929. Serial No. 360,636.

My invention relat'esft'o a ,new and improved method of and mechanism for makingcastings, and more particularly, dental Castings of the larger type such as bridge Work and the like.

` One ol the objects ofmy invention is to provide a method of making dental castings by the lost-Wax method whereby hot air under suitable pressure will be utilized l0 for forcing the molten metal into the cavity ofthe mold. instead of using ka Wax pattern iormaking the casting, l may use a hollow pyroXylin pattern Whose outer Wall has. been formed into the desired shape by means of This pyroxylin pattern can be removed by heating the mold and it has the advantage of leaving a cavity in the investlng lmaterial which has a smooth and dense Wall.

Another object ot my invention is to pro- 201vide a method whereby small castings, such as dental castings, can be quickly and uniformly'made in a denseand homogeneous form,

. and to also make it possible to make castings of metals having high melting points such as H palladium, platinum,"nickel and high melting alloys. Y

Another object of my invention is to permit the use of rareied hot air, or a rarelied hot gas for molding under pressure, the said hot air or hot gas havinga pressure which is lessthanthe normal pressure corresponding to the temperature of the air or gas utilized.

`While l do not Wish to limit myself to the gas which may be utilized, l prefer to use an vinert gassuch as nitrogen or carbondioxide.

y Another object of my invention is to pro- V vide a simplel device in which the heating of the hot air or gas utilized permits the operator to determine the temperature and presi sure ci the gas Whichis being utilized, Without making it necessary to add an expensive pyrometer to the apparatus.

Other objects of my invention Will be set forth inthe following description and drawings, which'illustratesJ preferred embodiment of my invention, it being understood that the above general statement of therebjectsofrmy V'invention is intended to .generally explainthe same and not to limit it in any manner.

Fig. l is a vertical sectional view, par-v tially in elevation, of a mechanism 4which meybe utilized to carry out my method.

1g. 2 is a sectional view on the line2-2 Fig. 3 is a detail View ofthemolding flask.

The casting oi' inlays'made of gold or other precious metals by the lost-Wax method has been Well known forniany years. In this method the mold is formed otdental investing material-in a suitable flask with the use ot'a Wax pattern. The Wax pattern is melted so that' it is either vap-orized or absorbed by the molding material, and then gold or other suitable metal must be forced :under-pressure into the molding'cavity, through a suitable sprue `which is formed`V in the` investing material. lt has: been proposed to'use coinpressed air forl forcing# the` molten' metal ln the methodsl previously used, the air o was utilized at comparatively low temperatures for-forcing the'molten metal into the mold so that the molten metal'vvas prerriaturely cooled Which resulted. in inaccurate castings.

According to my invention, I use a hotv gas or hot air'at a temperature of preferably 1:85" @-10600 C. although I may use` even higher temperatures, 'dependent upon the metal tol becast. This'. hot air or hot gas is used to vtorce the molten metal through the sprueintothe mold cavity. yInstead of using the hot airor the hot gas at the full pressure which would be caused by theI high temperature, l prefer toy r'arey the hotfair or hot gas by permitting some oi' it to escape before utilizing it for forcing the molten metal' intoV the mold cavity. The high temperature-of the air or gas alsoaprevents substantial amount thereof from being taken upfbyithe" hot metal, so that dense and homogeneousl castings can be secured. However, if air would be heated in a closed space to the above mentioned temperature, the pressure thereof would be too high. Hence,1 relieve the ressure of the air which is heated to the a ove mentioned temperature in a closed casing, so that air is' utilized which hasthe necessary high temperature without having too much pressure.

As shown in Fig. 1, a hollow casing 1 which may be heat insulated, is provided which has a depending` neck 5, which forms a chamber for receiving the molding flask 6. This molding liask may be of any lsuitable type and as illustrated herein, it is provided with a side .opening v10 forV receiving the dental investing material which serves as the mold. The pattern 11 is made of wax and it is formed in the usual manner. f

kAs illustrated in Fig. 3, the pattern 11 is utilized fory making a dental casting. It is connectedby means of the sprue wire12 to a cup 14 which-is supported upon the flange 19 of the flask 6. After the lwax pattern 11 has been surrounded by the dental investing material', the cup-shaped member 14 and the sprue w1re12 are removed, so that the top of the investing material located in the molding lflask 6, has a recess which communicates with the pattern l11 by means of a sprue opening corresponding to the Wire 12. When the wire 12 has been removed and the waX pattern 11 has beenmelted or driven off as previously i mentioned, molten metal can `be placed in the top rec-ess of the dental investing material, and this 'can be forced into the cavity corresponding to thefwax pattern 11, through the sprue corresponding to the wire12.

lThe molding flask 6 preferably rests upon va perforatedfstand 7 land thebottom of the .neck member 5 is preferably provided with perfor-ations 8 which` communicates with a tube -9 leading to the atmosphere.

rEhe casing 1 is provided with a core 3 made Y of suitable insulating material upon which an electric heating coil 2 is wound. The core 3 is held in position by means of a cap 4. A

jack 4a is utilizedk for connecting the heating coil 2 to any suitable source of electric current.y By means of this heating coil 2, the

.air within the casing l can be heated to any i Y desired temperature.

A tube 26 is connected to the casing v1. This tube 26 is provided with a dual gauge 18 `which indicates both pressure and temperature, being provided with two scales for this purpose; YThe tube 26 is provided with a re- A lief opening 16, controlled by a valve 17 so that some of the air within the casing 1 can be permitted to escape when tlre same is heated until the air in the casing -1 is at a 'temperature preferably not less than 500 C., `andhas a pressure of preferably notmore than 5-20 pounds per squareinch. The casto'py of the sleeve 22.

ing 1 is a source of heated 4gas under pressure, and this gas is used in casting or molding. operation. The pressure of the air or gas employed depends upon the size of the casting and it is preferably one pound per pennyweight if gold is being cast. t is to be understood that the pressures above mentioned are in excess ofthe atmospheric pressure. Heretofore, in a device of this type, it was necessary tooinstall an expensive pyrometer if the operator wishedto accurately deter- Vmine thelworking conditions. However, ac-

of an ordinary conversion table. The temperature of the air or gas depends on the metal or alloy which is being cast, a higher temperature being used with metals of high melting point. r1`he temperature of the gas or air is preferably the same as or sufficiently close to the melting point, to secure a perfect casting. f

The tube'26 is provided with a sleeve 22 which is upwardly urged by a compression spring 25. The sleeve 22 is provided with an opening which communicates with the bore of a lateral extension 21` of the hollow head 2O.Y When the sleeve 22 has been forcedto the lower or operative position in Fig. 1, against the force of the compression spring 25, the interior of thel head or cap 2O communicates with the interior of the pipe 26. However, when the sleeve 22 isin its upper position, then air can escape from the casing 1 and the tube,26, only through the relief opening 16. The sleeve 22 is adjacent the operating head 29 which has a quick internal thread, cooperating with the' corresponding external thread 27 at the top of the tube 26. The operating head 29 is provided with a handle 24, and with a pin 23 downwardly urged by the compression spring 27 to releasably enter a corresponding recess inthe e The sleeve 22 can turn upon the tube 26 so that the hollow cap 2O can occupy thepositions indicated in Fig. 2, at. B, C and A. In the position indicated by B in Fig. 2, the handle 24 is held by thespring latch32. The head 29 is connected to a torsion spring 28 whose upper end'isl suitably connected to the 'top of the tube 26, so that said torsion spring 28 tends to turn the handle 24 in the counterclockwise direction, to theposition A. stop 40-is provided to prevent the head or cap 20 from moving to the left of the position B, and a second stop 33 is provided to preventthe head n insee-,me

` the cap 2O and the handle 24are simultaneously moved to the position B.

The operation of the device is as follows: rl`he handle 24 is held in the position B.

' The thread 27 is aleft hand thread so .that

ture of said gas.

in this position the head 29 and the sleeve 22 are above the operative position shown in Fig. 1. Hence, the boreof. the lateral extension 21 does not communicate with the corresponding hole in the pipe 26 so that no air can escape save through the relief opening 16. The hole in pipe 26 can be provided with a valve to prevent leakage, this-valve being automatically opened when theparts are in the operative position shownin Fig. 1. The air within the casingis heated to a suitable temperature, preferably not less than 485"-300o C., and the valve 1'? is then opened to permit enough hot air to escape until the pressure indicated on the gauge 18 is about -20 pounds per square inch above the atmospheric pressure-,or even higher, depending on the metal utilized. It is a very important and novel feature of my invention to use a hot gas in the moldingfoperation, the pressure of said gas being less than the normal pressure corresponding to the tempera- In order to secure a gas having such characteristics, I have shown a source of heated gas comprising a casing having a heating element therein, and also having a relief valve, said casing being connected tothe molding flask by valve connected means. However, I do not wish to be limited to this specific devicel for producing a gas having said characteristics. The operator then places a lump of gold or other suitableV metal inthe top depression of the investing material, and he melts'the same'by anA ordinary blow-pipe, or the like. The sprue opening is too narrow to permit the i molten metal to pass into the cavity corresponding to the pattern 11. .The operator then pushes the handle 24 to the right, until it is released from the spring latch 32.- The torsion-spring 28 then quickly turns the head 29 until it occupies the position C. At this point, the head 20 yhas descended until the asbestos gasket 21 thereoffcontactswith the tapered top 190i1 the molding flask 6, thus starting to make an air-tight closure. The

torsion spring 28 then continues to turn the handle 24 and the head 29, into the position A. As the head 29 and the handle 24pass beyond the position "Cft`he head 22 no longer rotates so .that the further turning of the head 29, which is permitted by the reieaseeffnepin-se' from the head 20,;mereiy `4 serv-"es toi-downwardly force the sleeve 22 .so te further 'compress-the asbestos gasket mand prevent anyleakage of. air;y Of eeurse,

hotaiirhas' had'the desired .loss of pressure d fso-tliati'the hot air within the .Casing rushes j Y 'throu'glisthe bore; ofuthelateral:estension 21", i

andpasses through the fine holes inthe mem-` ber. 31;` '..Thehot 'airior'ces the. molten metal Aloe'atedin"thelrecess at the top of thegiirvestging material through .the spree opening. and inte .the cavity corresponding to the wax patterri 11j.; Arryleircessy ei' hotiair can escape rthrough the perforated stand? and. the openfings` p vWhen theeastingfhassb'een completed, it is merely necessaryy toturn the hand-'M124 to the position B,.whereuponthe moldingltlask can be readily removed. f j f. l. -1 i' For ctiifivenience,:v the pressure `oli thelair heatedlwitliinr the easing 1,. beoreanyoi the air is allowed to escape througlithe: opening 1.6, may` be designated as the normal pressure- ;corresponding. to vsaid temperature. IIoweveminfertain aspects. of my invention, ll-dof-notlwishitor be limited toithe use of air which. is. heated within. a closed-casing;

f- :If aniirertigas, suchasfcarhon dioxide: and

'nitrogen is'ito be used, thenlthe 'casing and accessory parts actin be .,lille'd with such inert' gas-'beorethe process i'sfstarted. j Likewise, 'lmaymseagaswhlch has a reducing action a-,rlfletemperatures @ir-PlOyCl-f .Th-mating i .coilinay hel-madeA el? any suitable materiah ,sucht nihhrome,.for platinunrwhichk can :withstand theV highf:tempeiature.v The flask which contains ,rsthe investing material and whic -has the opening 110 can have: 1a 1 door ftolosethesama 1 'WliilefjI-,hlave sho-wna preferred embodiament; otmy inventiomitis clear that numer- :ous changes :ande omissions could `be made without: departing fromV thek spirit thereoi'.v

I cla-imm.-

. 'g 1. dental casting. apparatus; 'comprising ies l 'fa casing adapted to forma -uid compression Y 1 chamberyarliafsk retaining member extending .i into-athefgcasing vand having its' lowerend Vconf-netedf-with theoutside of, the casing bya- 'iiuid conductingmeanseheating means within thel casingL te heat Vthe;y mold andi thel fluid kin theicompressionchamber, -a hollow head -rotatablf i, mounted on the :casing to'sealthe top l of:- theflask, and.n'ieans connected vwith thehollow-headandthe pressure chamberv to con- -..diictheated eempressedfud to thenpper end' cham-ber,- ai tubular member extending; into ,1 c 2 5.; dental casting apparatus",- cempri-sing,

a casing., adaptedtoforxnaflurd compression duit connected with the lower end of the tubuthe easing,f heating means within the casing l of the mold, conduit means connected with A.the casing and the hollow head to conduct I 5to heat a iuid in the compression-` chamber ,f and the mold, a hollow head rotatably mounty,

ed' on the casing and adapted'to seal the top Y heated compressed fluid to the upper end of the flask, and means onvthe conduit means to reduce the fluid pressure in the compression chamber. .f f 4 v 8. A dental casting apparatus comprising a casing adapted to form a fluid compression chamber, a flask retaining member extending y intothe casing and having its lower end connected with the. outside offthe casing by a luid conducting. means, heating means within the casing and surrounding the flask retaining member, a bored tubular member extere nally threaded intermediate its ends supported in the casing and connected with the compression chamber, an opening inthe tubular member intermediate its lower Aend and 'the ythreaded portion, a sleeve slidably and turn'- ably mounted on the lower endk of the tubular member, a lateral extension on the sleeve havinga bore therein and adapted to communicate with the opening in the tubular member, .a hollow head attached to the: lateral eXtension and adapted to seal the top of the mold, a compression spring interposed between the sleeve and casing, an internally ,threaded head, provided with a handle turnably mounted on the threadedv portion of l the tubular ymember adjacent the sleeve, avspring. pressed "spin in .the said head adapted to enter a recess in the top of the sleeve, va torsion spring mounted on the headand tubular member,

Vand adapted to turn the head and sleeve to bring the hollow head into operative-position,

whereby heated compressed Huid may pass j 5 through the tubular member, sleeve,lateral the tubular member adaptedto: register they temperatureand pressure of the Afluid in the compression chamber, and a reliei:` valve con- Vnected with the said chamber the fluid pressure.`

'4f-A dental casting apparatus,comprising a casing adapted to form a fluid compression lchamber, a flask retaining member extending l: to the casing and connectedtothe outside of thecasing by a fluid conducting means, heatfor regulating ing means within the casing to heat thepmold 4 sure .to the flask, and means to reduce the fluid Y pressure in the compression chamber. Y In testimony whereof I affix my slgnature.

and theiiuid in the compression chamber, a head vmovably mounted o n the casing to Aseal the adjacent end ofthe flask, and'means connected with the'head and, the compression chamber to conduct heated fluid under pres- MAXjs. sI-IAPIRO;V 

